Condensation tube for a blow-off device for limiting excess pressure in nuclear power plants, especially in boiling water nuclear power plants

Abstract

In a blow-off device for limiting excess pressure in nuclear power plants, a condensation tube disposed so that a lower outlet end thereof is immersed in a volume of water in a condensation chamber having a gas cushion located in a space above the volume of water, and an upper inlet end of the condensation tube extends out of the volume of water and is connectible to a source of steam that is to be condensed or a steam-air mixture, the outlet end of the condensation tube being further provided with a base member at the mouth of the outlet end for limiting steam flows discharging in axial direction of the tube, and being formed with lateral openings subdividing the steam flow and bubbles produced in the volume of water, the lateral outlet openings being formed of slots widening toward the end of the condensation tube, the slots being distributed over the periphery of the outlet end of the condensation tube.

There are claimed: 
     
       1. In a blow-off device for limiting excess pressure in nuclear power plants, a condensation tube for condensation of small mass flow densities disposed so that a lower outlet end thereof is immersed in a volume of water in a condensation chamber having a gas cushion located in a space above the volume of water, and an upper inlet end of the condensation tube extends out of the volume of water and is connectible to a source of steam that is to be condensed or a steam-air mixture, the outlet end of the condensation tube being further provided with a base member at the mouth of the outlet end for limiting steam flows discharging in axial direction of the tube, and being formed with lateral outlet openings subdividing the steam flow and bubbles produced in the volume of water, the lateral outlet openings being formed of slots widening toward the end of the condensation tube and, respectively, having the shape of an acute triangle, said slots being distributed over the periphery of the outlet end of the condensation tube, said base member being in the form of an insert member having a substantially conical contour with inwardly curved flow guidance surfaces, said insert member having an apex extending into the outlet end of the condensation tube, said insert member axially overlapping said slots. 
     
     
       2. Condensation tube according to claim 1 wherein the respective slots have a length that is 0.8 to 1.5 times the inner diameter of the condensation tube, and said triangular slots, respectively, have an apex defining an aperture angle of between 10° to 15°. 
     
     
       3. Condensation tube according to claim 1 wherein said slots, respectively, have the shape of an acute triangle, and wherein respective tube tongues remain between adjacent slots, said tongues having free ends abutting the base member at the tube mouth and being secured thereto by weldment. 
     
     
       4. Condensation tube according to claim 3 wherein respective mutually adjacent slots are spaced from one another in vicinity of the triangle base thereof by the width of the end of the respective tongues which is at least one-fourth the length of the triangle base. 
     
     
       5. Condensation tube according to claim 4 wherein the spacing between the slots at the base of the triangle-shape thereof, constitutes the width of the respective end of the tube tongue and is from about 1/2 to 1 length of said triangle base. 
     
     
       6. Condensation tube according to claim 1 wherein said substantially conical insert member has a height between the base and apex thereof that is at least 1/4 the height of the respective slots. 
     
     
       7. Condensation tube according to claim 6 wherein said height of said insert member is from 1/2 to 1/1 the height of the respective slots.